People are always pursuing more efficient energy storage devices which can provide high energy density, good power performance and long cycle life. The electrochemical double-layer capacitor (EDLC) contains two symmetrical activated carbon electrodes with high surface area and porous structure. Although the EDLC has the characteristics of high power and long cycle life, the energy density of an EDLC is less than 10% of that of a lithium-ion (Li-ion) battery (LIB), which restricts its application in the field of hybrid electric vehicles (HEVs), electric vehicles (EVs) and other large-scale energy storage systems.
Therefore, in recent years considerable research has been focused on the development of a high energy density EDLC. Among all the energy storage systems that have been investigated and developed in the last few years, Li-ion Capacitors (LICs) have emerged to be one of the most promising because LICs achieve higher energy density than conventional EDLCs, and better power performance than LIBs as well being capable of long cycle life. LICs contain a “pre-lithiated” LIB anode electrode and an EDLC cathode electrode. Fuji Co. proposed using a separate lithium foil as the third electrode to pre-lithiate the anode electrodes and the first company which utilized a third electrode of lithium metal to pre-lithiate the anode and produce the LICs was JM Energy and the energy density of their LICs reached approximately 10 Wh kg−1 with very stable long cycle life.
Stabilized lithium metal powder (SLMP) is a pioneering and revolutionary material and technology developed by FMC that is able to provide electrochemically energy carrier as rechargeable lithium atom for all types of lithium based energy devices. SLMP is comprised of spherical particles with controlled particle size and surface area. SLMP is made by agitating a mixture of molten lithium metal in a hydrocarbon oil at dispersion speeds. The thickness and chemistry of the protective coating layer can be tailored and engineered based on user preference. SLMP can offer a capacity as high as 3600 mAh g−1 and still can be safely introduced to the energy storage devices in a dry room atmosphere. SLMP has been widely used in the LIB energy storage system for pre-lithation of the anode electrodes including hard carbon, soft carbon, graphite and nano-silicon electrodes.
Another lithium source that is used widely in lithium-metal battery is the thin lithium films as the negative electrodes. Among all the energy storage devices, one of the most spotlighted high performance cutting-edge batteries is the lithium-metal battery, which can be classified as lithium-ion or lithium sulfur batteries. The reason for choosing lithium as anode is that the density of lithium is as low as 0.54 g/cm3 and the standard reduction potential is low (−3.045 V SHE (Standard hydrogen electrode)), which enables lithium to be promising high energy density electrode material.
In this respect, before explaining at least one embodiment of the invention in detail it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be considered to be, or regarded as limiting.